Regulation of cytokinetic machinery in plants

Plant cells divide by constructing a two-dimensional membrane compartment filled with oligosaccharides known as the cell plate. The cell plate is produced by the phragmoplast, a plant-specific structure composed of cytoskeletal polymers, membranes, and associated proteins. Initially, the phragmoplast forms as a disk between daughter nuclei at the end of anaphase, then continues to expand outward until the cell plate connects to the parental cell wall. Phragmoplast expansion encompasses dramatic reorganization of microtubules. At the start, microtubules form short antiparallel overlaps that initiate cell plate biogenesis by recruiting membrane material in the form of cytokinetic vesicles. Subsequent membrane expansion and remodeling processes are accompanied by dissolution of the antiparallel overlaps and attachment of microtubules to the cell plate biogenesis machinery. Deposition of oligosaccharides into the lumen confers mechanical rigidity to the cell plate that triggers depolymerization of microtubules. Precise coordination of microtubule organization with vesicle trafficking, membrane remodeling, and the deposition of oligosaccharides plays a critical role for cell plate production. This review summarizes current understanding of key signaling pathways that couple diverse processes in the phragmoplast.